Here is the data table for the performance of this vat. It only has the option of full power on or off so these results should pretty consistent. I used one gallon of water in the water jacket and five gallons of water in the batch pan.

Please note that milk may have different thermal properties than water so it could heat faster or slower than what is depicted here.

This graph will expand if you click on it.(Please note that the power was cut at 50 minutes)

Here is the data table which is probably more useful beyond just visualizing the relationship between the two temps. I'm not sure why I can't get this to show up bigger... it will expand slightly if you click on it.

Conclusions#1- For a five gallons, the Batch Temperature should lag predictably by 11 degrees behind the Water Jacket Temperature.#2- The residual/carry over temperature of the batch from the time the unit cuts off should be about 8 to 10 degrees if the Jacket is leading by the full 11 degrees. This would be most useful when setting the temperature for ripening the milk. #3- This thing heats much too quickly to cook curd slowly so I would recommend bumping it up a degree or two at a time and letting the temperature equalize. Keeping the Jacket Temp closer to the Batch Temp will slow down the process.#4- The most important residual temp/carry over number is the Water Jacket. It was only 3 degrees with an 11 degree differential between it and the Batch. The carryover would likely be higher if the Batch was closer to it's temp because the batch wouldn't absorb as much of the heat.

#5- After all of this, I think what Ive realized is that unless you can control the amount of heat the element is producing, you can never "set it and forget it." That being said, this setup should be an easy way to control your temperature in a very precise way without taking your vat in and out of the water. If anyone else ends up using this set up, I be very interested to hear your insights on how to most effectively put this thing to work.

I use it for curing meats which requires a lot tighter tolerances but the setup works very well. (I took the basic design from some research I did on several other people's work... I'm not trying to take credit for the design, I just thought I could explain it in detail so people didn't have to do as much research as I did when I started.)

Sorry for the late reply. This is all just a hobby and tinkering for me so I'm really not prepared to start building and selling them. That is why I put my design out there for everyone. I have suggested to a couple of people that they might try finding a handyman on Craigslist. This project only needs someone with a few basic (though specialized) tool and the ability to read a wiring diagram. That is probably cheaper than me trying to build and ship them.

If anyone needs help finding the exact parts, I am glad to help.

The warming unit itself is a standardized depth of about seven inches or so. It is only designed to accommodate a six inch deep hotel pan. I have not tried it but I think an 8" hotel pan could work just fine and give you additional capacity. You would just need something in the bottom of the unit, in the water, to lift the pan off of the bottom but still allow the water to circulate. The 8" deep pan would then stick out the top a couple of inches but that should not be an issue since so much of the surface area is in contact with the water. (Sorry, I don't have time at the moment to post pics but if anyone is unsure of what I am describing for an 8" deep hotel pan, let me know and I'll detail it with pics.)

I really like the concept.I already found all the parts.I actually think there might be a way to add the digital control without all the hacking.I haven't decided yet if this is the way I'm going to go or not.As for the 8' pan a few 2" strips of Stainless and a few beers to bribe my buddy will get me a spacer.For a test you could probable frame it with wood.

Sort of kicking around an idea to use a immersion element and a high temp recirculation pump setup in such a way as to be portable from one pot to another allowing me to up size without much hassle.Any double boiler combo would work.The only thing going in the pot would be a suction line and a return line all the mechanical would be under the counter.

But I do like the scale of your device while what I'm thinking of can go from small to very large without much effort.

This is another way of using precisely the same little 'box of tricks'. Between my father and my son it has now been wired up as a standalone gadget that can be plugged into any appliance, either to limit heating of a heater, or to limit cooling of a fridge or freezer. So far I have only tried it once yesterday afternoon, on my slow cooker. This proved less than satisfactory as the pottery insert of the slow cooker heated up substantially before the 4 litres of water within it heated, and after reaching temp of 25C and switching off (gadget working perfectly here) the pottery then released its heat into the water and raised it another 5c before it started cooling down again.

Here is the front of the 'gadget'.It is mounted in a box for electrical safety.From left to right, the connections are: white socket for cooling items, white socket for heating items, black temperature gauge (pop it into whatever you want to measure the temp of), and white plug to go in the wall socket.

And here is the back - thanks Dad for a lovely neat and safe job! Heating and cooling sockets are more clearly marked than the photo suggests

Now I just need to tour Ebay and the local op shops until I find something more suitable to connect it up to... I'm thinking something like a canning water bath, and use a metal (or my usual plastic) container within that to hold the milk but without the heat retaining properties of the slow cooker's pottery inner.

That is a brilliant piece of work! It is a much simpler solution to work with that box than to cut stainless... Plus, it is more versatile. I use a temp controller from a keg refrigerator for my curing/ aging boxes (another thread) and it is great but it doesn't control a heater if it gets too cold. This would control both heating and cooling...

I understand what you are saying about your cooker carrying over. I think when it comes to this kind of precise temperature control, especially if you are trying to automate it, heat sinks and carryover temperature are the enemy. I would think it would be ideal to have a thin steel wall with lots of surface area in contact with the water jacket. Then, as little water as possible, while still maintaining the surface heating area.

Simply put, you want to buffer the heating element so it heats evenly but you want the system to store as little energy as possible so when the element shuts off, the heating stops quickly.

I know you get that already. It is just one of those things I didn't think of at the beginning either.

Thanks all. And Jason - the better mousetrap award goes to my dad really, for fathoming out how to turn the idea into reality!

And this afternoon I scored a large urn-type canning unit on ebay, the type with an element in the bottom and a tap on the side for draining. In a few days when I have collected that I will be able to see how it works as a temp-regulated water bath.

Just collected my flippin' big pot and and I think the last laugh may be on me... it already has a thermostatic control that takes it from 24C (75F) to boiling! The size seems just perfect, here it is with my 10 litre bucket inside, that I use to make an 8 litre (2 gal) batch of cheese.

The lid even fits on with my bucket inside, which should help with temp regulation. Oh and it's stainless, another big plus.

Inside, there is an exposed element in the base with a loose perforated plate over. Looks like I may have to organise a trivet so the heat can circulate efficiently in the water bath rather than sit the bucket directly on here.

I've proved it's working, now to set it up with the gadget - which will allow greater precision with temps than the dial, and will let me use Celsius which is what I am familiar with as the dial is in Fahrenheit.

Let me ask a couple of questions about the portable steam table. I am in the Philippines and was looking at buying a very similar model in the USA and having it shipped here for doing a low cost sous vide setup. I was planning on using an Aubers or similar PID unit to control the temperature when using it as a sous vide unit. Wouldn't that setup work for using it as a cheese vat as well?

Is there a pressing reason or advantage to do the cut and install of a PID controller instead of using a version that plugs into the power? Lastly, how do you get the water out after you are finished? I saw a somewhat more expensive version with a drain tap. Would that be a better choice for ease of use? Or would it have drawbacks that I am not familiar with?

I had started out looking at the 18 or 20 quart roaster ovens, but the steam table looks like an even better choice. I may go for one of each, so we have a back up and my wife can use the roaster for outings.

Since I have to pay a hefty shipping bill (and risk damage to the unit in transit), I really want to make the best selection I can. Any guidance on the best choices and approach will be greatly appreciated.

Tatoosh

Belated Update: The model of steam table I am looking at is a Alfa FW9000 seen here: FW9000 A bit pricier but workable with a PID controller like an Aubers?